The invention concerns a roll type mower conditioner with two rolls located adjacent each other which define a gap or nip between them for taking in crop that is to be processed and where at least one of the rolls has its opposite ends supported in bearings respectively provided in a pair of pivotally mounted arms and is yieldably restrained from moving away from the other roll by an external force.
Roll conditioners with two counter-rotating rolls are used, among other applications, to compress crop such as corn, grass or the like so that moisture or nutrients contained therein can be excreted. Accordingly, such roll conditioners can be found assembled with mowers or ensilage harvesters.
U.S. Pat. No. 3,820,311 granted to Sawyer et al on 28 Jun. 1974 discloses a so-called mower conditioner having a transverse beam supporting a cutterbar which is followed by a pair of conditioning rolls. Both conditioning rolls are provided with an embossed rubber coating, with the upper of the two rolls being supported at both ends in pivoting arms. A tensioning mechanism comprises a linkage connected to each arm and a helical extension spring connected to each linkage such that the arms are biased toward, and the upper roll is urged against, and yieldably restrained from moving away from, the lower roll. In this way, pressure sufficient to process the crop is applied to the crop flowing between the two rolls.
This patent is representative of art wherein an increase in the thickness of the mat of crop flowing between the rolls forces the upper roll away from and thus results an increase in the space between the two rolls and a corresponding increase in the spring force which not only increases the pressure on the crop passing between the rolls but also on the rubber coating. In the case that a foreign object, such as a stone or branch, is introduced between the two rolls, the rubber coating may be damaged if the pressure exceeds a certain value.